How can we acquire knowledge of metaphysical modality? How can someone come to know that he could have been elsewhere right now, or an accountant rather than a philosophy teacher, but could not have been a turnip? Jago proposes an account of a route to knowledge of the way things could have been and must be. He argues that we can move to knowledge of metaphysical modality from knowledge about essence. Curtis rejects Jago’s explanation. It cannot, he argues, explain our knowledge of de re necessity. We agree. But there is more to be said. To give an account of our knowledge of metaphysical necessity is part of the task Jago set himself. But another part is to give an account of the knowledge of the (non-actual) possibilities accorded to particular objects. And prior to both what is needed, and something Jago attempts to supply, is an account of how ordinary knowers can come to have knowledge of an individual’s essential properties. We argue that Jago’s accounts of both these additional matters are also unsatisfactory. This is important because the thought that our knowledge of metaphysical modality has its source in our knowledge of essence is currently an attractive one and Jago has set out very clearly what must be done to justify the thought. The flaws in his proposal thus indicate the work needed if the attractive thought is to be accepted.

我们如何获得形而上学形态的知识？怎么会有人知道他现在本可以在别处，或者是会计而不是哲学老师，但不可能是萝卜？Jago 提出了一条通往了解事物本来可以和必须成为的方式的途径。他认为，我们可以从关于本质的知识转向形而上学形态的知识。柯蒂斯拒绝了贾戈的解释。他认为，它不能解释我们对必要性的认识。我们同意。但还有更多要说的。说明我们对形而上学必然性的认识是 Jago 自己设定的任务的一部分。但另一部分是对（非实际）可能性的知识进行说明赋予特定对象。在需要什么以及 Jago 试图提供什么之前，先说明普通知识者如何能够了解个人的基本属性。我们认为 Jago 对这两个额外问题的描述也不令人满意。这一点很重要，因为我们对形而上学形态的知识源于我们对本质的知识的想法目前是一个有吸引力的想法，并且 Jago 已经非常清楚地阐述了必须做些什么来证明这种想法是正确的。因此，他的提议中的缺陷表明，如果要接受有吸引力的想法，还需要做一些工作。